Electrically maintained pendulum motors, particularly for clocks



June '17, 1952 2,600,754

S. GOLD ELECTRICALLY MAINTAINED PENDULUM MOTORS, PARTICULARLY FOR CLOCKS Filed Aug. 8, 1950 I ATTORNEYS Patented June 17, 1952 ELECTRICALLY MAINTAINED PENDULUM MOTORS, PARTICULARLY FOR CLOCKS Solomon Gold, Wimbledon, London, England Application August 8, 1950, Serial-No. 178,245 'In Great Britain August 15, 1949 (cognate) 7 Claims.

This invention relates to electrically maintained pendulum motors, particularly for clocks.

.It'is an object of the invention to provide an improved form and construction of pendulum motor which has a high electrical efficiency, and is also simple and cheap to manufacture; the pendulum is at the same time very reliable in operation, adaptable as regards current supply and is robust.

According to the invention an electrically maintained pendulum motor comprises a pendulum, a ratchet wheel and pawl mechanism for causing the oscillation of the pendulum to rotate the ratchet wheel, electromagnetic impulsing means for the pendulum, and a contact device controlling the current fed to the impulsing means, which contact device is actuated by the ratchet wheel and produces a single impulse at predetermined intervals, each greater than the period Of oscillation (two swings) of the pendulum.

There is further provided according to the invention an electrically maintained pendulum motor comprising a pendulum, a ratchet wheel and pawl mechanism for causing the oscillation of the pendulum to rotate the ratchet wheel, electromagnetic impulsing means for the pendulum, and a rotating contact device controlling the current fed to the impulsing means, which contact device is driven by the ratchet wheel and produces a single impulse at predetermined intervals, each greater than the period of oscillation (two swings) of the pendulum.

Preferably the contact device comprises a moving contact member which moves in a circular orbit and a fixed contact member which is engaged by the moving contact member once for each revolution of the ratchet wheel. Thus the moving contact member may comprise a pivotally mounted roller made of conducting material, the axis of the roller being moved in a circular orbit by the ratchet wheel, said roller being arranged to engage a pair of fixed contact members once during each revolution of the ratchet wheel and to form a conducting bridge between them.

The invention is illustrated in the accompanying drawings, in which- Figure .1 is a rear View of an electric clock mechanism;

Figure 2 is a side view looking in the direction of the arrow A in Figure 1;

Figure 3 is a perspective View Of the ratchet wheel and its associated contact device, the foundation plate of the mechanism being omitted;

lid

Figure 4 is a diagram of the electrical connections; and

Figure 5 is a side elevation of a modified construction of ratchet wheel incorporating contactclcaning means, the contact members being shown in section.

The clock mechanism shown in Figures 1 and 2 is arranged to be operated from any of the usual mains supplies of electricity, either A. C. or D. 0.; with a suitably wound electromagnet it can operate from a low voltage supply, such as a dry battery.

It comprises a foundation plate 18 made of electrical insulating material, such as synthetic resin, fitted within the usual clock case (not shown) by means of pillars I I so as to be rigidly held in a substantially vertical plane. The pendulum, which is indicated generally at I2 is in the form of a sheet metal stamping forming a pendulum rod 13, to the upper end of which is secured a spring suspension is carried upon a bracket i5; at its lower end the pendulum .rod carries a transverse pin H5 upon which hangs a stem ll fitted with an adjustable bob weight it will be seen that the pendulum .rod [3 is shaped with a cranked portion [9 which is onset from the plane of oscillation of the pendulum, indicated at 23. dulum to swing past an electromagnet 21 which is mounted within a slot in the foundation plate is and comprises a straight iron core 22 surrounded by a flat cylindrical coil 23 in the form of a bobbin wound with insulated copper wire in the normal manner. The core 22 lies in line with the axis of the pendulum when the latter is at the mid-point of its stroke, said core having an exposed pole at each end. These co-operate with an armature 24 which is also made of .iron and comprises a U-shaped stamping having its base portion 25 secured to the offset portion HI of the pendulum rod 13, while its limbs 28 are turned through a right angle and are arranged to sweep past the ends of the core It will be seen that when the electromagnet Al is energised, the

in IE.

armature 24 forms an efficient path for the magnetic flux and so a powerful pull is produced with relatively little expenditure of current; also the attraction operates directly towards the core 22 and as this lies substantially in the plane of oscillation 2i! of the pendulum, the attraction does not produce any rolling motion.

In order to utilise the motion of the pendulum l2 and to control the supply of current which is fed intermittently to the electromagnet 2|, the pendulum is arranged to rotate a ratchet wheel This is to allow the pen- 21 also disposed in the plane of oscillation 26. It has a tubular spindle 28 which is freely revolvable upon a pin 28 carried by a bracket 39. The ratchet wheel 2'! has a small odd number of teeth (say 7) and is advanced by half a tooth during each swing of the pendulum l2. For this purpose the pendulum rod I3 is fitted with two rigid pawls 3| and 32 which are L-shaped and which project outwards in opposite directions from the pendulum rod I3 to form arcuate locking surfaces 3|a and 32a which alternately slide chordwise across the tooth spaces at the top and bottom of the ratchet wheel 21. This form of ratchet mechanism is described more fully in my British patent specification No. 624,681. As a safety measure in case the ratchet wheel 2! should tend to move backwards, the spindle (which passes freely through a large hole in the plate H3) is formed with a ratchet pinion 3-3 having fine teeth which are engaged by a detent 34 freely pivoted to the plate ID at 35 (see Figure 3). The ratchet wheel 2'! may drive the going train of the clock in any desired manner; in the form shown the safety ratchet pinion 33 has two pins 35 projecting from its end to act as a twotooth pinion engaging a gear wheel 31, which in turn has two pins 38 engaging the minute wheel 39. The motion work is of the usual form indicated at 46 and is provided with a hand-setting spindle 4|.

The contact-making devic associated with the ratchet wheel 21 is shown most clearly in Figure 3. A small cylindrical roller 42, made of electricity-conducting material, preferably carbon,

mounted to be freely rotatable upon a pin 43 ex- (3 tending parallel with the spindle 23; the roller thus travels in a circular orbit as the ratchet wheel 21 rotates, said ratchet wheel making one complete revolution for each seven oscillations of the pendulum 2. Fixed to the plate In by slotted lugs 44, 45 are two contact strips 46, 41 made of thin springy metal, their free end parts being disposed side by side (but not touching one another) just in front of the ratchet wheel 21. These end parts are bent to form in each a downward corrugation or bulge, these bein shown at 48 and 49, and being arranged at such a distance from the spindle 28 that they are lightly swept by the roller 42 as the ratchet wheel 21 turns. Thus for a short period during each revolution the roller 42 forms a contact bridge connecting together the strips 46 and 41; at the same time the roller 42 turns on its pin 43 so that a fresh surface is presented to the strips 45, 41 at each revolution. In order that the ratchet wheel 2! shall be balanced, a lead pellet 50 of suitable size is fitted into a hole in the ratchet wheel 2! at a position diametrically opposite to the pin 43. The ratchet wheel 2'! is preferably made of fibre or plastic so as to form an insulated mounting for the roller 42 and also to reduce the operating noise and avoid the necessity of lubricating the teeth.

The electrical connections of the clock are shown in Figure 4. Three contact pins 5|, 52 and 53 are fitted in a line to the casing of the clock (not shown) and are engageable by a fitting 54 having three sockets 55, 56 and 51. The sockets 55 and 56 are coupled to a flexible twin supply lead 58 and the fitting 54 is reversible so that although the live socket 56 always connects with the centre pin 52, the other live socket 55 engages the pin 5| in one position of the fitting 54, and the pin 53 when the fitting 54 is inverted. Thus provision is made for running the clock on a voltage of approximately 110 when the fitting 54 is disposed as shown, and on a voltage of approximately 220 when the fitting 54 is inverted. The pin 52 is connected by a wire 59 with the contact strip 46, while the contact strip 41 is connected by wire 60 to the electromagnet 2|; the other end of this coil is connected by a wire 6| to the pin 5| and also through a voltage-dropping resistor 62 to the pin 53. Thus whenever the contact strips 46, 41 are bridged, current flows through the electromagnet 2| and energises it. The roller 42 is so positioned with respect to the teeth of the ratchet wheel 21 that this energisation commences while the armature 24 is approaching the core 22 and the circuit is broken just before the core is reached. A capacitor 63 (say .005 mfd.) is connected across the contact strips 46, 41, while a capacitor 64 (say .1 mfd.) is placed across the contact device 46, 41 and the electromagnet 2|, both of these serving to reduce sparking and radio interference.

When the clock is connected to the supply mains and the pendulum set in motion, the periodic energisation of the electromagnet 2| keeps the pendulum swinging with ample power to drive the usual hands (not shown) of the clock through the gearing 3640.

If desired means may be provided for cleaning the contact strips 46, 4! automatically and one suitable arrangement is shown in Figure 5. At a position diametrically opposite to the roller 42, the ratchet wheel 21 is fitted with a small rod of abrasive material such as Carborundum. This sweeps lightly across the contact surfaces of the strips 45, 47 once during each revolution of the ratchet wheel 27 but as it is non-conducting it does not complete the circuit.

It will be understood that the above mechanism is described only by way of example and that various modifications may be made to suit requirements. Although the invention is espeoially applicable to clocks, the pendulum motor may be used for driving any other light mechanism.

The improved device is found to operate very satisfactorily on either A. C. or D. C. and any given coil will work with any supply within a relatively large voltage range. The energy consumed is very small as the circuit is completed for only a minute fraction of the running time and the rating of the electromagnet is of the order of only one or two watts.

What I claim is:

1. An electrically maintained pendulum motor comprising a backplate, a pendulum, a ratchet and pawl mechanism for causing the oscillation of the pendulum to rotate the ratchet wheel. electromagnetic impulsing means for the pendulum, and a contact device controlling the current i" ed to the impulsing means, which contact device is operated by the ratchet wheel and produces a single impulse at predetermined intervals, each greater than the period of oscillation of the pendulum, and which iinpulsing means comprise an electro-magnet element on the backplate, having a straight core made of magnetic material disposed in a plane which is radial with respect to the pendulum swing, and a U-shaped armature on the pendulum, the extremities of the two limbs of which armature cooperate respectively with the inner and outer ends of the electromagnet core, and the pendulum comprising a pendulum rod which is cranked intermediate its ends, the axis of the electromagnet being disposed substantially in the plane of oscillation of the pendulum and the cranked portion of the pendulum rod being arranged to pass beside the electromagnet as the pendulum swings.

2. A pendulum motor as claimed in claim 1, wherein the U-shaped armature is attached to the cranked portion of the pendulum rod, the limbs of the armature extending horizontally one above the electromagnet and one below it.

3. An electrically maintained pendulum motor comprising a backplate, a pendulum, a ratchet wheel and pawl mechanism for causin the oscillation of the pendulum to rotate the ratchet wheel. electromagnetic impulsing mean for the pendulum, a rotating contact device controlling the current fed to the impulsing means, which contact device is driven by the ratchet; wheel and produces a single impulse at predetermined intervals, each greater than the period of oscillation of the pendulum, said contact device comprising a roller made of conducting material and pivotally mounted upon the ratchet wheel, the axis of the roller being moved in a circular orbit by the ratchet wheel, and a pair of fixed contact members which are mounted on the backplate and are engaged by the roller once for each revolution of the ratchet wheel, so that said roller forms a conducting bridge between them.

4. A pendulum motor as claimed in claim 3, having a pin fixed eccentrically upon the ratchet 6 wheel, the roller being tubular and being pivoted upon said pin.

5. A pendulum motor as claimed in claim 4, wherein the movin contact member comprises a roller made of carbon, arranged to form a conducting bridge between a pair of fixed metal contact members extending side by side each tangentially with respect to the orbital movement of the carbon roller.

6,. A pendulum motor as claimed in claim 5, wherein the fixed contact members comprise resilient fingers made of thin strip metal so as to be deflected easily by the roller.

7. A pendulum motor as claimed in claim 6, wherein each fixed contact member has a bulge or offset portion which is engaged by the carbon roller.

SOLOMON GOLD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 345,720 Parcelle July 20, 1886 1,483,814 J uruick Feb. 12, 1924 

